Electrosurgery involves the application of radio-frequency (RF) electrical energy to cut a patient's tissue, to coagulate blood flow from the tissue, or to both cut and coagulate simultaneously. An electrosurgical generator creates the RF electrical energy, and the RF energy is applied to the tissue by an applicator or pencil-like handpiece which is manipulated by a surgeon to cut and coagulate. Gas-assisted electrosurgery additionally involves conducting the RF energy to the tissue in a stream of ionized conductive gas. The gas stream clears blood and other fluids from the surface of the tissue, thereby allowing the RF energy to interact directly with the tissue without the fluid diverting all or part of the electrical energy away from the tissue. The transfer of the RF energy through the ionized gas stream directly to the tissue without diversion from fluid achieves an enhanced electrosurgical effect. U.S. Pat. No. 4,781,175 and Re U.S. Pat. No. 34,780 are exemplary of gas-assisted electrosurgery apparatus. Both of these U.S. patents are assigned to the same assignee as the present application.
A nozzle at the distal end of the handpiece shapes the gas into a flow stream of desired characteristics. An electrode is positioned within the nozzle to ionize the gas and to transfer the RF energy into conductive pathways within the gas stream. An accessory hose conducts the gas flow from a gas delivery apparatus to the nozzle, and an accessory conductor conducts the RF energy from an electrosurgical generator to the electrode within the nozzle. The accessory hose and conductor and the nozzle and electrode are part of the gas-assisted electrosurgical accessory.
An accessory connector connects the accessory hose and conductor to a housing of a gas-assisted electrosurgical unit, which includes the electrosurgical generator and gas delivery apparatus. The accessory connector permits different gas-assisted electrosurgical accessories to be used and replaced as necessary or desirable. One mating piece of the accessory connector is connected to the accessory handpiece, and another complementary mating piece of the accessory connector is connected to the housing of the gas-assisted electrosurgical unit. The accessory connector transfers the gas flow and RF energy from the gas-assisted electrosurgical unit into the accessory hose and onto the accessory conductor of the accessory.
In some gas-assisted electrosurgery accessories, such as probes used in gastrointestinal electrosurgical applications, the pencil-like handpiece and the cord are either not used or they are considerably modified in form. For example, in a gas-assisted gastrointestinal electrosurgical probe, the accessory hose takes the form of a small diameter gas-conducting tube that extends directly from the accessory connector to the end of the gas-conducting tube where the nozzle is located. The accessory conductor extends within the gas conducting tube. No pencil-like handpiece exists, because the end of the gas-conducting tube with the nozzle and the internal electrode is manipulated by an endoscope or a laparoscope into which the probes inserted. A gastrointestinal probe of this type is an example of a gas-assisted electrosurgery accessory used to perform minimally invasive electrosurgical procedures. A variety of other types of accessories using handpieces and different lengths of cords and different configurations of nozzles are available to perform other open types of electrosurgical procedures.
The accessory connector should transfer the gas flow and the RF electrical energy without leakage to the ambient environment. In a typical gas-assisted electrosurgical procedure, the surgeon selects a desired gas flow and a desired amount of electrosurgical energy to be applied to the tissue. In many cases, the amount of gas flow and the amount of the electrical energy are coordinated to achieve a desired electrosurgical effect. If gas leaks from the accessory connector, the desired amount of gas will not be delivered from the nozzle, and the desired electrosurgical effect may not be achieved. Similarly, if current leakage or conduction of some of the RF energy occurs at the accessory connector, the desired electrosurgical effect may not be achieved. RF energy leakage at the accessory connector or any other location along the cord or within the handpiece, can cause an unintended burn to the surgeon, operating room personnel or the patient, or may damaged the electrosurgical generator.
An example of a gas-assisted electrosurgery accessory connector is described in U.S. Pat. No. Re 34,780. The gas sealing capability of the accessory connector described in this U.S. patent is achieved by an axial contact seal. The gas-confining integrity of such a seal depends upon the two mating pieces of the accessory connector remaining in an axially forced-together relationship. Such a relationship is achieved by screwing together the complementary threads of the two mating pieces until the two sealing surfaces axially contact one another. While this threaded-together relationship provides an effective gas-tight axial contact seal in most circumstances, it is possible for the threaded connection of the two mating pieces to loosen over the relatively lengthy duration of many surgical procedures due to the continual movement of the cord and the handpiece. It is not unusual for the threaded connection to loosen if the cord is accidentally stepped on, pulled or bumped by operating room personnel while performing the surgical procedure. Loosening of the two connected mating pieces of the accessory connector, even to a small degree, is likely to cause the sealing surfaces of the accessory connector to separate slightly, resulting in a leak gas.
The surgeon and the operating room personnel are not likely to recognize a leak at the accessory connector. The surgeon's attention is focused almost exclusively on creating the desired affects at the surgical site. The surgeon depends almost exclusively on the operating room personnel to supply the necessary equipment for use when the surgeon needs that equipment. In addition to serving the needs of the surgeon, the operating room personnel are focused on many other responsibilities associated with the surgical procedure, such looking after and monitoring as the welfare of the patient. The tissues encountered during a typical electrosurgical procedure vary substantially in electrical impedance and vascularity, both of which have a significant impact on the electrosurgical effect achieved. Since the surgeon expects variations in the surgical effect due to tissue differences, the surgeon may not recognize that the performance of the gas-assisted electrosurgical unit may have become compromised as a result of a gas leak at the accessory connector, resulting from continual movement of the cord and the handpiece during the procedure or from the cord having been accidentally stepped on, pulled or bumped during the surgical procedure.
The problems of gas leaks at the accessory connector may be aggravated with gas-assisted gastrointestinal electrosurgical probes. A relatively small diameter gas-conducting tube is required for insertion into an instrument channel of the endoscope or laparoscope. The endoscope or laparoscope must be relatively narrow to permit it to be inserted within a lengthy hollow organ in the gastrointestinal tract or to be inserted within an inflated body cavity. The gas flow rate through the relatively small diameter gas-conducting tube is less, causing the effect of a relatively small leak to magnify the extent of deviation of the gas flow from the nozzle, thereby impacting the expected performance.
These and other considerations have led to the improvements of the present invention.